This invention relates generally to water treatment technology and more specifically to methods and apparatus for dissolving oxygen in wastewater such as water received for purification in municipal sewage plants and the like.
The conventional activated sludge process for the treatment of wastewater involves the biological degradation of organic materials contained therein. This requires the maintenance of aerobic conditions, normally achieved by relying on open aeration to dissolve oxygen from ambient air into wastewater. While such processes have been used successfully for many years there are definite limits on the speed and efficiency of such processes. For example both the rate at which oxygen can be dissolved in the water and the maximum oxygen concentration that can be achieved are clearly limited. As a result the ever expanding needs for more and better wastewater treatment to protect the ecology in our expanding society can be met, using existing processes, only by a proliferation of plants for such processes at great capital expense and with the utilization of vast quantities of power in their operation.
The present invention is directed to methods and apparatus for more quickly and efficiently dissolving oxygen in wastewater to accelerate the biodegradation of organic material. This, in turn, increases the through-put of any given treatment facility and reduces the unit cost of wastewater treatment.
Cost reduction can be effected even though oxygen or oxygen enriched air (which costs money) is utilized in place of air (which is "free"). However, to keep the treatment cost to a minimum, the oxygen must be used efficiently, i.e., a high percentage of the oxygen supplied must be dissolved in and retained by the wastewater.